"www.testwww.com".replace("www.", ""); //this will replace the first occurrence of "www." and return "testwww.com"
"www.testwww.com".slice(4); //this will slice the first four characters and return "testwww.com"
"www.testwww.com".replace(/^(www\.)/,""); //this will replace the www. only if it is at the beginning